JP5759359B2 - Liquid filled vibration isolator - Google Patents

Description

  The present invention relates to a liquid-filled vibration isolator used for automobiles, industrial machines and the like.

  Liquid-sealed devices have been used as anti-vibration devices such as engine mounts, transmission mounts, suspension bushings, and motor mounts used in automobiles and industrial machines. For example, as shown in FIG. 4, the engine mount includes an upper holding member 1 attached to an engine that is a vibration source, and a lower holding member 2 attached to a vehicle body, a frame, and the like. It is integrated through the body 4. A diaphragm 5 is attached to the lower holding member 2, and a liquid sealed space for storing the liquid P in a sealed state is formed between the diaphragm 5 and the vulcanized rubber molded body 3. Further, the liquid sealed space is divided into two upper and lower chambers, a main liquid chamber 9 and a sub liquid chamber 10, by a partition member 8 in which an orifice 7 is formed, and the liquid P passes through the orifice 7 between the two chambers. To flow through. In addition, 11 and 12 are bolt screws for attachment, respectively (for example, refer patent document 1).

  According to this configuration, even if the vulcanized rubber molded body 3 receives the vibration of the engine, it is transmitted to the vehicle body side by the vibration absorbing action by its own elasticity and the flow action of the liquid P in the liquid sealed space. Vibration is damped.

  By the way, in recent years, technological innovation in the automobile industry has been remarkable, and extremely quiet running is being realized compared to the past, but if the engine is subject to large vibrations due to the unevenness of the road surface, the main rubber elastic body will be greatly elastically deformed Abnormal noise and vibration caused by the shock wave generated when cavitation is generated in the pressure receiving chamber due to cavitation and the shock wave generated when the bubble disappears is transmitted to the vehicle because the pressure in the pressure receiving chamber rapidly decreases significantly. Is a problem.

  Therefore, as a method for suppressing the occurrence of such cavitation, a device such as a relief valve is provided to reduce the pressure difference between the main liquid chamber 9 and the sub liquid chamber 10, or a high vapor pressure (= A method (for example, refer to Patent Document 2) or the like for suppressing the pressure drop in the main liquid chamber 9 by adding a liquid having a low boiling point and vaporizing the high vapor pressure liquid under a negative pressure has been proposed.

JP 2005-337348 A International Publication No. 2009/154222

  However, when a device such as the relief valve is provided, if the valve is opened to suppress cavitation, the pressure difference between the main liquid chamber 9 and the sub liquid chamber 10 becomes small, and the damping performance is exhibited while passing through the orifice 7. Since the amount of movement of the liquid P is reduced, there is a problem that the damping performance is lowered, and the anti-vibration effect that is the original purpose cannot be sufficiently obtained.

  In addition, in the method of adding a high vapor pressure liquid described in Patent Document 2, the boiling point of the liquid to be added is low. The added liquid is boiled, and a large amount of gas is resident in the liquid chamber, thereby causing a reduction in vibration-proof performance and expansion and rupture of the diaphragm, resulting in a problem in product function.

  The present invention has been made in view of such circumstances, and is an excellent liquid-filled vibration isolator capable of effectively suppressing cavitation causing abnormal noise without impairing the vibration isolating effect. The purpose is to provide.

  In order to achieve the above object, a liquid-filled vibration isolator according to the present invention includes a liquid sealed space for containing a liquid in a sealed state, and a partition for partitioning the liquid sealed space into a plurality of chambers in a state where they are communicated with each other through an orifice. A vulcanized rubber molded body that forms at least a part of the liquid sealed space, and a holding member that holds the vulcanized rubber molded body, and the vibration transmitted to the vulcanized rubber molded body is A liquid-filled vibration isolator configured to be attenuated by elastic deformation of the vulcanized rubber molded body itself and liquid flow between the chambers, wherein the liquid includes a first liquid made of a polar organic solvent, and the first liquid A mixed gas containing a second liquid composed of a polar oil having compatibility with one liquid and having surface activity and a foamable powder is used, and a dissolved gas derived from a gas generated from the foamable powder. Vaporization Properly by liquefaction, a configuration that the pressure fluctuations in the liquid sealing space due to elastic deformation of the vulcanized rubber molding is enabled relaxation.

  The inventors of the present invention have conducted research on a method for suppressing cavitation in a liquid-filled vibration isolator without impairing the vibration isolating effect. As a result, it was found that when the gas generated under negative pressure is dispersed as a plurality of bubbles, the generation of large bubbles is suppressed and cavitation due to the burst of large bubbles does not occur. As a result of further research, in order to disperse the gas into a plurality of bubbles in order to suppress the generation of large bubbles, a conventional polar organic solvent such as ethylene glycol is compatible with this and has an interface. It has been found that when polar oil having active performance is blended as the second liquid, the surface tension of the whole liquid is lowered, and bubbles generated in the liquid are broken before being enlarged and divided into a plurality of parts. As a gas source for generating the bubbles, if a foamable powder that can generate a gas by natural decomposition or heating is included in the liquid in advance, the gas generated from the foamable powder dissolves in the liquid. Therefore, when the liquid sealed space becomes negative pressure, the dissolved gas is vaporized, and when the negative pressure is eliminated, the vaporized dissolved gas is dissolved again in the liquid, and pressure fluctuation in the liquid sealed space is effective. It was found that the present invention was relaxed and an excellent cavitation suppression effect was obtained, and the present invention was achieved.

  That is, the liquid-filled vibration isolator of the present invention includes a first liquid made of a polar organic solvent and a polar oil that is compatible with the first liquid and has a surface-active performance as the liquid sealed in the device. Since the mixed liquid containing the second liquid and the expandable powder is used, the surface tension of the entire liquid is lower than that of the conventional liquid, and is generated by the decomposition of the expandable powder under a negative pressure. Since the bubbles derived from the dissolved gas dissolved in the gas are generated in a plurality of states and the generation of large bubbles that cause cavitation is suppressed, an excellent cavitation suppressing effect can be obtained. And, since the generation of noise due to cavitation is suppressed without impairing the original vibration isolation performance associated with the fluidity of the device, it is possible to keep quiet in the environment where the vibration isolation device is installed, such as the car body. it can.

  In the present invention, in particular, the first liquid is composed of at least one of ethylene glycol and propylene glycol, and the second liquid is at least one of polyether oil, polyether-modified silicone oil, and vinyl oil. The liquid-filled vibration isolator, which is a kind of polar oil, is particularly excellent in cavitation suppression effect because the generated gas is divided into a plurality of bubbles and easily grows under negative pressure.

  Further, in the present invention, in particular, the liquid is formed by blending 0.1 to 80 parts by weight of the second liquid and 0.01 to 2 parts by weight of the foamable powder with respect to 100 parts by weight of the first liquid. Since the liquid-sealed vibration isolator using the mixed liquid has a more preferable liquid property, it has an excellent cavitation suppressing effect.

  Among the present invention, in particular, the foamable powder is composed of sodium hydrogen carbonate, potassium hydrogen carbonate, sodium hypochlorite, magnesium carbonate, calcium carbonate, dry ice, ammonium hydrogen carbonate, ammonium carbonate, and calcium peroxide. The liquid-filled vibration isolator, which is at least one foamable powder selected from the group consisting of, is sufficient for the dissolved gas in the liquid derived from these foamable powders to alleviate pressure fluctuations in the liquid sealed space. It is preferable because it can be dissolved in a liquid in an appropriate amount.

It is a longitudinal cross-sectional view which shows one embodiment of this invention. It is typical explanatory drawing of the method of measuring the transmission load of an engine mount. (A) is a diagram which shows the anti-vibration performance of the Example goods of this invention, (b) is a diagram which shows the anti-soaking performance of a comparative example goods. It is sectional drawing which shows the conventional liquid enclosure type vibration isolator.

  Next, embodiments of the present invention will be described in detail. However, the present invention is not limited to this embodiment.

  An embodiment of the present invention is shown in FIG. This liquid-filled vibration isolator is attached to a vehicle body, a frame, or the like via a first holding member 20 attached to an engine as a vibration source via a bolt (not shown) and a predetermined attachment member (not shown). A substantially cylindrical second holding member 21 to be attached is integrated via a vulcanized rubber molded body 22. In addition, a diaphragm 23 is attached in a liquid-tight state inside a lower end opening of the second holding member 21, and a liquid-sealed liquid P is accommodated between the vulcanized rubber molded body 22 and the diaphragm 23 in a sealed state. A space is formed.

  The liquid sealed space is partitioned into two upper and lower chambers of a main liquid chamber 25 and a sub liquid chamber 26 via a partition member 24, and the main space is divided by an orifice 27 provided at the peripheral edge of the partition member 24. The liquid chamber 25 and the sub liquid chamber 26 are communicated with each other.

  Therefore, according to the above configuration, when the vulcanized rubber molded body 22 receives the vibration of the engine, it is transmitted to the vehicle body side by the vibration absorbing action due to its own elasticity and the flow action of the liquid P in the liquid sealed space. The vibrations that occur are attenuated to a very low level, and excellent vibration-proofing performance is exhibited.

  In addition, in this apparatus, as the liquid P to be sealed in the liquid sealed space, a first liquid made of a polar organic solvent and a second liquid made of polar oil that is compatible with the first liquid and has surface activity ability. And a liquid mixture containing foamable powder. This is a major feature of the present invention.

  As the polar organic solvent used as the first liquid, ethylene glycol (hereinafter referred to as “EG”) alone, propylene glycol (hereinafter referred to as “PG”) alone used as a liquid sealed in a liquid filled type vibration isolator. Alternatively, a mixed liquid thereof or the like can be used. In addition, glycol solvents such as butyl diglycol, methyl triglycol, butyl triglycol, and methyl polyglycol, or water or other polar fluids can be used. Especially, it is suitable to use the liquid mixture of EG and PG, and the thing whose mixing ratio (EG: PG) is 50: 50-90: 10 is especially suitable.

  Examples of polar oils that are used as the second liquid and that are compatible with the first liquid and have surface-active performance include polyether oils, polyether-modified silicone oils, and vinyl oils. . These may be used alone or in combination of two or more. These need not be easily vaporized, and those having an average molecular weight of 2000 to 8000 are usually preferably used. Of these, polyether-modified silicone oil is particularly preferable from the viewpoints of compatibility with the first liquid and surface active performance.

  The phrase “having compatibility” means that the second liquid has an affinity for the first liquid, and the liquid obtained by mixing the two becomes a uniform one-phase liquid. In addition, the above-mentioned “having surface active performance” means that the molecule has a hydrophilic part and a lipophilic part, and has the ability to lower the interfacial tension at the interface of two liquids that do not melt together. Say.

  As the foamable powder used together with the first liquid and the second liquid, a gas is generated by natural decomposition, heating, reaction with oxygen in the air, etc., and the gas is mixed with the first liquid and the first liquid. It must be dissolved to some extent in the two liquid mixture and exist as a dissolved gas. Examples of such effervescent powder include sodium hydrogen carbonate, potassium hydrogen carbonate, sodium hypochlorite, magnesium carbonate, calcium carbonate, dry ice, ammonium hydrogen carbonate, ammonium carbonate, and calcium peroxide. Ammonium bicarbonate having a high solubility and a large amount of gas generation is preferably used. These may be used alone or in combination of two or more.

Incidentally, the reaction formula for generating gas in each of the foamable powders is as follows.
(1) Sodium bicarbonate ₂ NaHCO ₃ → Na ₂ CO ₃ + H ₂ O + CO ₂ ↑
(2) Potassium bicarbonate 2KHCO ₃ → K ₂ CO ₃ + H ₂ O + CO ₂ ↑
(3) Sodium hypochlorite 2NaClO → 2NaCl + O ₂ ↑
(4) Magnesium carbonate MgCO ₃ → MgO + CO ₂ ↑
(5) Calcium carbonate CaCO ₃ → CaO + CO ₂ ↑
(6) Dry ice CO ₂ (solid) → CO ₂ (gas) ↑
(7) Ammonium bicarbonate NH ₄ HCO ₃ → NH ₃ ↑ + H ₂ O + CO ₂ ↑
(8) Ammonium carbonate (NH ₄ ) ₂ CO ₃ → 2NH ₃ ↑ + H ₂ O + CO ₂ ↑
(9) Calcium peroxide 2CaO ₂ + 2H ₂ O → 2Ca (OH) ₂ + O ₂ ↑

  The foamable powder may be preliminarily contained in the first liquid, may be contained in the second liquid, or may be contained in the mixed liquid of the first liquid and the second liquid. Since the amount of gas generated before sealing the liquid is released and dissolved as a dissolved gas in the liquid is reduced, it is preferable that the liquid mixture of the first liquid and the second liquid is blended immediately before the liquid is sealed. .

  As described above, the foamable powder generates a gas by natural decomposition or heating as described above, and this gas is contained as a dissolved gas in the liquid. By vaporizing or liquefying according to the fluctuation, the pressure fluctuation is reduced.

  In addition, when the first liquid is a mixture of a plurality of liquids such as EG and PG, and is used as a dissolved gas by slightly entraining air during the mixing, the dissolved gas is also Similar to the dissolved gas derived from the foamable powder, it is preferable because it repeats vaporization and liquefaction along with the pressure fluctuation in the liquid sealed space to help ease the relaxation.

  The mixing ratio of the first liquid, the second liquid, and the foamable powder is 0.1 to 80 parts by weight of the second liquid and 0.01 to 2 parts by weight of the foamable powder with respect to 100 parts by weight of the first liquid. It is preferable to set. That is, if the amount of the second liquid is less than the above range, the surface tension of the entire liquid P is not lowered so much that bubbles are not easily generated. If it exceeds the range, the gas generated from the powder is not completely dissolved in the liquid, and the gas is present in the product, which is not preferable. If the expandable powder is less than the above range, the gas generated from the expandable powder, and thus the content of dissolved gas derived therefrom, is reduced, making it difficult to obtain a sufficient pressure fluctuation mitigating action. If the foamable powder is more than the above range, the amount of gas dissolved in the liquid is limited, which is not preferable because the gas exists in the liquid and affects the vibration isolation performance.

  In addition to the first liquid and the second liquid, a foam suppressant, an antioxidant and the like can be added to the liquid P as optional components. Furthermore, in order to assist the pressure fluctuation mitigating action of the dissolved gas derived from the foamable powder, a gas such as carbon dioxide, ammonia, oxygen or the like is introduced into the liquid P by aeration in advance and contained as a dissolved gas. Also good.

  As described above, the present invention uses the special liquid P as the liquid P sealed in the liquid sealed space, so that the entire surface tension of the sealed liquid P is lower than that of the prior art, and the foaming is performed under a negative pressure. Since a plurality of bubbles derived from the gas generated from the conductive powder are generated in a state of being separated in the liquid, an excellent cavitation suppressing effect can be obtained. And, since the generation of noise due to cavitation is suppressed without impairing the original vibration isolation performance associated with the fluidity of the device, it is possible to keep quiet in the environment where the vibration isolation device is installed, such as the car body. it can.

  Next, an example of a method for producing the engine mount will be described.

  First, a mold for molding the vulcanized rubber molded body 22 is prepared, and the first holding member 20 and the second holding member 21 are set at predetermined positions of the mold. The first holding member 20, the second holding member 21, and the vulcanized rubber molded body 22 are integrated by heating after filling the unvulcanized rubber composition that is the material of the vulcanized rubber molded body 22. To do. Next, a diaphragm 23 that has been heat-molded in advance is prepared, and the first holding member 20, the second holding member 21, and the vulcanized rubber molded body 22 are integrated in the liquid tank in which the liquid P is stored. The partition member 24 and the diaphragm 23 are fitted from the lower end opening of the second holding member 21 and attached to a predetermined position, and then taken out from the liquid tank. In this way, the liquid P is sealed between the vulcanized rubber molded body 22 and the diaphragm 23. Thereafter, the lower end portion of the second holding member 21 is caulked to completely seal the liquid P. In this way, the engine mount can be obtained.

  The above example is one example in which the liquid-filled vibration isolator of the present invention is applied to an engine mount. However, the engine mount is a suspended type and an upright mounted type. There is no problem. Further, the present invention can be applied to various vibration isolators such as an engine mount, an automobile suspension bush, and a motor mount.

  Next, examples will be described together with comparative examples.

[Examples 1 to 11, Comparative Example 1]
An engine mount similar to that shown in FIG. 1 was prepared using the liquid P sealed in the liquid sealed space having the composition shown in Tables 1 and 2 below.

  As shown in FIG. 2, the obtained engine mount A was attached to the vibration device 30 via an attachment member 32, and mount displacement was input by simulating mounting on an automobile. And the load at the time of vibration was read with the load sensor 31, and the transmission load (N) was measured through the high-pass filter (500 Hz). And the transmission load of each Example 1-11 goods when the transmission load of 1 comparative example goods was set to 100 was calculated, and the result was combined with the following Table 1 and Table 2, and was shown.

  From the above results, it can be seen that the products of Examples 1 to 11 have a smaller transmission load than the product of Comparative Example 1 and have excellent vibration isolation performance.

  For reference, the measurement result of the product of Example 1 is shown in FIG. 3A, and the measurement result of the product of Comparative Example 1 is shown in FIG.

  The present invention is a liquid-filled vibration isolator such as an engine mount, a mission mount, a suspension bush, and a motor mount used for automobiles, industrial machines, etc., and in particular, the generation of abnormal noise due to cavitation is effectively suppressed. It can be used for anti-vibration devices.

20 First holding member 21 Second holding member 22 Vulcanized rubber molded body 23 Diaphragm 24 Partition member 25 Main liquid chamber 26 Sub liquid chamber 27 Orifice P Liquid

Claims (4)

  Liquid sealed space for storing liquid in a sealed state, a partition for partitioning the liquid sealed space into a plurality of chambers in communication with each other through an orifice, and a vulcanized rubber molded body forming at least a part of the liquid sealed space And a holding member for holding the vulcanized rubber molded body, and vibration transmitted to the vulcanized rubber molded body is attenuated by elastic deformation of the vulcanized rubber molded body itself and liquid flow between the chambers. A liquid-filled vibration isolator configured to perform a first liquid composed of a polar organic solvent and a polar oil that is compatible with the first liquid and has surface-active performance. A mixed liquid obtained by mixing two liquids and an expandable powder is used, and the vulcanized rubber molded body is elastically deformed by vaporizing or liquefying a dissolved gas derived from a gas generated from the expandable powder. Liquid-filled vibration damping device, characterized in that the pressure variation is enabled relaxation in the Hare liquid sealing space.   2. The first liquid is made of at least one of ethylene glycol and propylene glycol, and the second liquid is at least one polar oil of polyether oil, polyether-modified silicone oil, and vinyl oil. Liquid filled vibration isolator.   The said liquid is a mixed liquid formed by mix | blending 0.1-80 weight part of 2nd liquid, and 0.01-2 weight part of foamable powder with respect to 100 weight part of 1st liquids. Liquid filled vibration isolator.   The foamable powder is at least one foam selected from the group consisting of sodium bicarbonate, potassium bicarbonate, sodium hypochlorite, magnesium carbonate, calcium carbonate, dry ice, ammonium bicarbonate, ammonium carbonate and calcium peroxide. The liquid-filled vibration isolator according to claim 1, wherein the liquid-filled vibration isolator is a conductive powder.

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